Spring属性占位符PropertyPlaceholderConfigurer的使用

Spring属性占位符PropertyPlaceholderConfigurer的使用
1、一个简单的Demo
1.1、创建conf.xml

<?xml version="1.0" encoding="UTF-8"?>

<!DOCTYPE beans PUBLIC "-//SPRING//DTD BEAN//EN" "http://www.springframework.org/dtd/spring-beans.dtd">

<beans>

<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">

<!--

使用location属性定义单个配置文件

<property name="location">

<value>classpath:/com/zsw/config/jdbc.properties</value>

</property>

-->

<!-- 使用locations属性定义多个配置文件 -->

<property name="locations">

<list>

<value>classpath:/com/zsw/config/jdbc.properties</value>

</list>

</property>

</bean>

<bean id="dataSource" class="org.springframework.jdbc.datasource.DriverManagerDataSource">

<property name="url">

<value>${database.url}</value>

</property>

<property name="driverClassName">

<value>${database.driver}</value>

</property>

<property name="username">

<value>${database.user}</value>

</property>

<property name="password">

<value>${database.password}</value>

</property>

</bean>

</beans>
1.2.创建jdbc.properties文件

database.driver=com.mysql.jdbc.Driver

database.url=jdbc:mysql://localhost:3306/right?useUnicode=true&autoReconnect=true&characterEncoding=UTF-8

database.user=root

database.password=root

jdbc.pool.c3p0.acquire_increment=2

jdbc.pool.c3p0.max_size=20

jdbc.pool.c3p0.min_size=2

jdbc.pool.c3p0.preferred_test_query='SELECT 1'

jdbc.pool.c3p0.idle_connection_test_period=18000

jdbc.pool.c3p0.max_idle_time=25000
1.3.创建Config.java

package com.zsw.config;

import org.springframework.beans.factory.config.PropertyPlaceholderConfigurer;

import org.springframework.beans.factory.xml.XmlBeanFactory;

import org.springframework.context.ApplicationContext;

import org.springframework.context.support.ClassPathXmlApplicationContext;

import org.springframework.core.io.FileSystemResource;

import org.springframework.jdbc.datasource.DriverManagerDataSource;

public class Config {

public static void main(String[] args) {

XmlBeanFactory factory = new XmlBeanFactory(new FileSystemResource("src/com/zsw/config/conf.xml"));

// 如果要在BeanFactory中使用，bean factory post-processor必须手动运行:

PropertyPlaceholderConfigurer cfg = new PropertyPlaceholderConfigurer();

cfg.setLocation(new FileSystemResource("src/com/zsw/config/jdbc.properties"));

cfg.postProcessBeanFactory(factory);

DriverManagerDataSource dataSource = (DriverManagerDataSource) factory.getBean("dataSource");

// System.out.println(dataSource.getDriverClassName());

System.out.println(dataSource.getUsername());

// 注意，ApplicationContext能够自动辨认和应用在其上部署的实现了BeanFactoryPostProcessor的bean。这就意味着，当使用ApplicationContext的时候应用PropertyPlaceholderConfigurer会非常的方便。由于这个原因，建议想要使用这个或者其他bean

// factory postprocessor的用户使用ApplicationContext代替BeanFactroy。

ApplicationContext context = new ClassPathXmlApplicationContext("com/zsw/config/conf.xml");

DriverManagerDataSource dataSource2 = (DriverManagerDataSource) context.getBean("dataSource");

System.out.println(dataSource2.getUsername());

}

}

2.Spring中PropertyPlaceholderConfigurer多种配置方式

2.1配置单个Properties文件

<bean id="propertyConfigurerForAnalysis" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">

<property name="location">

<value>classpath:/spring/include/dbQuery.properties</value>

</property>

</bean>

其中classpath是引用src目录下的文件写法。

2.2 当存在多个Properties文件时，配置就需使用locations了：

<bean id="propertyConfigurer" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">
<property name="locations">
<list>
<value>classpath:/spring/include/jdbc-parms.properties</value>
<value>classpath:/spring/include/base-config.properties</value>
</list>
</property>
</bean>

2.3、接下来我们要使用多个PropertyPlaceholderConfigurer来分散配置，达到整合多工程下的多个分散的Properties 文件，其配置如下：

<bean id="propertyConfigurerForProject1" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">

<property name="order" value="1" />

<property name="ignoreUnresolvablePlaceholders" value="true" />

<property name="location">

<value>classpath:/spring/include/dbQuery.properties</value>

</property>

</bean>

<bean id="propertyConfigurerForProject2" class="org.springframework.beans.factory.config.PropertyPlaceholderConfigurer">

<property name="order" value="2" />

<property name="ignoreUnresolvablePlaceholders" value="true" />

<property name="locations">

<list>

<value>classpath:/spring/include/jdbc-parms.properties</value>

<value>classpath:/spring/include/base-config.properties</value>

</list>

</property>

</bean>

其中order属性代表其加载顺序，而ignoreUnresolvablePlaceholders为是否忽略不可解析的 Placeholder，如配置了多个PropertyPlaceholderConfigurer，则需设置为true